SpaceX is on target to return to flight with the Jan. 8 launch of an Iridium NEXT communications satellite owned by Iridium Communications. The launch will take place at Vanderberg Air Force Base’s Space Launch Complex in California.
This will be the first launch for Elon Musk’s aerospace operation since the Sept. 1 explosion of the Falcon 9 rocket and its Amos-6 satellite payload.
SpaceX said Tuesday it worked with officials at the Federal Aviation Administration, the U.S. Air Force, the National Aeronautics and Space Administration, the National Transportation Safety Board, and industry experts to determine the cause of the anomaly.
This investigation team concluded the failure was likely due to the accumulation of oxygen between the composite overwrapped pressure vessel liner and overwrap in a void or a buckle in the liner, leading to ignition and the subsequent failure of the COPV, SpaceX said in a statement.
“Each stage of Falcon 9 uses COPVs to store cold helium, which is used to maintain tank pressure, and each COPV consists of an aluminum inner liner with a carbon overwrap,” said the SpaceX statement.
“The recovered COPVs showed buckles in their liners. Although buckles were not shown to burst a COPV on their own, investigators concluded that super chilled [liquid oxygen] can pool in these buckles under the overwrap. When pressurized, oxygen pooled in this buckle can become trapped; in turn, breaking fibers or friction can ignite the oxygen in the overwrap, causing the COPV to fail. In addition, investigators determined that the loading temperature of the helium was cold enough to create solid oxygen, which exacerbates the possibility of oxygen becoming trapped as well as the likelihood of friction ignition.”
The investigation took about four months, SpaceX said.
“Investigators scoured more than 3,000 channels of video and telemetry data covering a very brief timeline of events – there were just 93 milliseconds from the first sign of anomalous data to the loss of the second stage, followed by loss of the vehicle,” said the SpaceX statement.
“Because the failure occurred on the ground, investigators were also able to review umbilical data, ground-based video, and physical debris. To validate investigation analysis and findings, SpaceX conducted a wide range of tests at its facilities in Hawthorne, Calif., and McGregor, Texas.”
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